Hydrocarbon-producing wells often are stimulated by hydraulic fracturing operations, wherein a fracturing fluid may be introduced into a portion of a subterranean formation penetrated by a well bore at a hydraulic pressure sufficient to create or enhance at least one fracture therein. Stimulating or treating the well in such ways increases hydrocarbon production from the well.
In some wells, it may be desirable to individually and selectively create multiple fractures along a well bore at a distance apart from each other. The multiple fractures should have adequate conductivity, so that the greatest possible quantity of hydrocarbons in an oil and gas reservoir can be drained/produced into the well bore. When stimulating a reservoir from a well bore, especially those well bores that are highly deviated or horizontal, it may be difficult to control the creation of multi-zone fractures along the well bore without cementing a casing or liner to the well bore and mechanically isolating the subterranean formation being fractured from previously-fractured formations, or formations that have not yet been fractured.
To avoid explosive perforating steps and other undesirable actions associated with fracturing, certain tools may be placed in the well bore to place fracturing fluids under high pressure and direct the fluids into the formation. In some tools, high pressure fluids may be “jetted” into the formation. For example, a tool having jet forming apertures or nozzles, also called a “hydrojetting” or “hydrajetting” tool, may be placed in the well bore near the formation. The jet forming nozzles create a high pressure fluid flow path directed at the formation of interest. In another tool, which may be called a tubing window, a stimulation sleeve, or a stimulation valve, a section of tubing includes holes or apertures pre-formed in the tubing. The tubing window may also include an actuatable window assembly for selectively exposing the tubing holes to a high pressure fluid inside the tubing. The tubing holes may include jet forming nozzles to provide a fluid jet into the formation, causing tunnels and fractures therein.
The fluid jetting apertures or nozzles in the fluid jetting tools are in fixed positions in the tool body. For example, a hydrojetting tool may have one or more high pressure fluid paths therethrough with nozzles affixed at the outlet of each fluid path. The nozzles are located at various fixed locations about the tool body. In another example, a stimulation sleeve may include multiple fluid jetting apertures also in fixed positions about the sleeve body. Often times a good fluid treatment or fracturing operation will require creating numerous holes in the formation, above and/or below the original position of the fluid jetting tool. Further, aligning the additional formation holes created by the tool prevents tortuous formation fracture paths that twist between randomly located holes. To create numerous fracturing holes along a well bore, a fluid jetting tool may need to be moved from its original deployed and activated position to a position above or below the original position, where additional holes can be made. A fluid jetting tool deployed on a work string, such as coiled tubing, is moved by pulling up on the work string. However, pulling up on the work string by a few inches or more does not translate to similar movement by the fluid jetting tool. Friction between the work string and the well bore prevents uphole movement of the work string from translating smoothly to movement of the fluid jetting tool, if at all. Moreover, it is desirable for the fracturing holes to be aligned or angled in a precise manner. The awkward and clumsy tugging and rotating of the work string cannot ensure such precision.
To achieve desirable results in the aforementioned fluid treatment processes, increased control over the fluid jetting process is needed. Such needed control is pushing the limits of current fluid treatment systems. The present disclosure includes embodiments for increased fluid jetting control, for example, by downhole-initiated movement of the fluid jets.